ITHACA, NEW YORK — About 640 light-years from Earth, an ultra-hot Jupiter — a gas giant with an orbital period less than 10 days — may be even hotter than scientists realized, according to a new study in the Astrophysical Journal Letters, cited by Space.com.
Previous studies have noted that WASP-76 b sits close to enough to its star to complete an orbit every 1.8 Earth days, and is tidally locked, meaning its nightside temperature could be around 1,300 degrees Celsius, and its dayside may be around 2,400 degrees.
One effect of the extreme proximity is that the huge amounts of stellar radiation that WASP-76 b absorbs has blown it up to 1.85 times wider than Jupiter despite the fact it carries just 85 percent of Jupiter’s mass.
However, famously, a second effect is that temperatures on the ‘day side’ of the planet are hot enough to vaporize iron and this iron condenses once it reaches the cooler ‘night side,’ falling as molten iron rain.
The new study adds to this hellish picture with the discovery of ionized calcium in WASP-76 b’s upper atmosphere, with its lead author explaining in a statement on Queen’s University Belfast’s website that this “could indicate that the exoplanet has very strong upper atmosphere winds, or the atmospheric temperature on the exoplanet is much higher than we thought.”